Skin is exposed to damage resulting from various sources, including both environmental factors and biochemical processes. Oxidative processes damage proteins, lipids, and other cellular components necessary to maintain the health and appearance of skin, resulting in skin changes, such as skin aging, hyperpigmentation, UV damage, lines, wrinkles, uneven skin texture, etc. Oxidative damage to the skin and its more detailed causes are described in Myachi, Y., “Skin Diseases Associated with Oxidative Injury,” In: Fuchs, J., Packer, L. (eds.), “Oxidative Stress in Dermatology.” Marcel Dekker, New York, pp. 323-331 (1993).
The damaging effects of the UV part of solar radiation on the skin are generally known. While rays having a wavelength less than 290 nm (the UVC range), are absorbed by the ozone layer in the earth's atmosphere, rays in the range between 290 nm and 320 nm (the UVB range), cause an erythema, simple sunburn or even more or less severe burns. The narrower range around 308 nm is given as a maximum for erythema activity of sunlight. For protection against UVB radiation, numerous compounds are known, including derivatives of 3-benzylidene camphor, 4-aminobenzoic acid, cinnamic acid, salicylic acid, benzophenone, and 2-phenylbenzimidazole. Also, for the range between about 320 nm and about 400 nm (the UVA range) it is important to have filter substances available, since UVA rays can cause reactions in light-sensitive skin. It has been demonstrated that UVA radiation leads to damage of the elastic and collagenic fibers of the connective tissue, which allows the skin to age prematurely, and that it is to be regarded as a cause of numerous phototoxic and photoallergic reactions. The damaging influence of UVB radiation can be amplified by UVA radiation. It has also been demonstrated that consumption of lipophilic antioxidants, for example, alpha-tocopherol, is triggered in the skin by UVA and UVB radiation. Thiele, J. J., Traber, M. G., Packer, L., “Depletion of human stratum corneum vitamin E: an early and sensitive in vivo marker of UV induced photo-oxidation,” J. Invest. Dermatol. 110:756-761 (1998).
Further, UV radiation is ionizing radiation. Hence, there is the risk that ionic species are produced upon UV exposure, which are then able to intervene oxidatively in the biochemical processes.
For protection against the rays of the UVA range, certain derivatives of dibenzoylmethane have therefore been used, the photostability of which is not provided to an adequate extent. Deflandre, A., Lang, G. “Photostability assessment of sunscreens. Benzylidene camphor and dibenzoylmethane derivatives,” Int. J. Cosm. Sci. 10(2):53-62 (1988). UV radiation, however, can also lead to photochemical reactions, wherein then the photochemical reaction products intervene in the skin mechanism.
Predominantly such photochemical reaction products are free radical compounds, for example hydroxyl radicals. Also, undefined free radical photoproducts, which are produced in the skin itself, can trigger uncontrolled side reactions due to their high reactivity. Singlet oxygen, a non-free radical excited state of the oxygen molecule, however, can occur in UV irradiation, short-lived epoxides and many others. Singlet oxygen, for example, is characterized with respect to the normally existing triplet oxygen (free radical base state) by increased reactivity. Nevertheless, excited, reactive (free radical) triplet states of the oxygen molecule also exist. Furthermore, there is the occurrence of lipid peroxidation products, such as hydroperoxides and aldehydes, wherein first in turn free radical chain reactions can be triggered and to which overall cytotoxic properties have been ascribed. Michiels, C., Ramacle, J., “Cytotoxicity of linoleic acid peroxide malondialdehyde and 4-hydroxynonenal towards human fibroblasts,” Toxicology, 66:225-234 (1990). Lipid peroxidation is an oxidative process that degrades lipids, wherein free radicals steal electrons from the lipids in cell membranes, causing oxidative stress and cell damage.
Light-sensitive skin includes the disorder photodermatoses (photosensitive eruptions). Further designations for the polymorphic light-dermatosis are PLD, PLE, Mallorca Acne and a plurality of further designations, as are given in the literature. Voelckel, A., et al., “Vorkommen und Photo-Isomerisierung der Urocaninsaure im Stratum Corneum bei polymorpher Lichtdermatose (PLD). Vergleichende Untersuchung bei PLD-Patienten und Hautgesunden,” Zentralblatt Haut-Und Geschlechtskrankheiten (1989), Springer-Verlag, vol. 156, 1989, pp. 1-15. Erythematous skin symptoms also occur as concomitant symptoms in certain skin diseases or skin irregularities. For example, the typical rash in the clinical picture of acne is regularly reddened to a greater or lesser extent.
It is known that undesirable oxidation processes can occur in the human and animal skin. Such processes play a considerable part in skin aging. In order to prevent these reactions, antioxidants and/or free radical absorbers/scavengers can be incorporated in cosmetic or dermatological formulations to treat or prevent damage caused by oxidative and/or degenerative biochemical processes. Antioxidants are substances that scavenge free radicals and prevent oxidation processes or prevent the auto-oxidation of fats containing unsaturated compounds. Antioxidants used in the field of cosmetics and pharmacy include, for example, alpha-tocopherol, in particular in the form of alpha-tocopheryl acetate, sesamol, colic acid derivatives, butylhydroxy anisole, butylhydroxy toluene, vitamin C, plant-derived polyphenols and flavonoids, and idebenone. For example, it has been proposed to use vitamin E (U.S. Pat. Nos. 4,144,325 and 4,248,861), a substance having known antioxidative action in sunscreen formulations, but even here the action achieved remains far below that hoped for. Tocopherol (a vitamin E antioxidant), for example, degrades to form pro-oxidative products.
While antioxidants and/or free radical absorbers/scavengers have been included in cosmetic and/or dermatological compositions, none of these compositions provide complete protection against undesirable oxidation processes because none contain the proper blend of botanical antioxidant extracts necessary to provide a broad spectrum of antioxidant protection that can significantly (e.g., synergistically) increase the capacity for oxidative stress protection.